What about a product can irritate you?

Power switches on the back are, purportedly, so the component is left on all the time... there's also some macho marketing involved methinks. The switch in front wouldn't bother the "on all the time" scheme now, would it:)

Practicality in design:

one pre I used, had the two pre OUTputs on EITHER side of "pro in", at the back of the unit, the unit being large and deep of course (so, no visibility from front). So, 9/10 when I changed IC, one of the amps was mute OR one channel on one amp was mute -- and I'd invariably get a small heart attack wondering what the H blew and why... until I realised I'd connected the pro-in.

The Thiel engineering hurdle, as per Ketchup above. To visualise the problem, think of THICK cable and trying to screw it on UNDER each spkr, when the nut rolls away... majestic!

The Valve Conundrum, as per Redkiwi:

*Am I burning IN or burning OUT?????

The "deep class A" solid-state challenge:

*whether 'tis better to leave it on all the time and foot the bill and risk burn out if high ambient temperatures BUT enjoy the music at guise OR, switch it off/on as required and sleep at nights and stick to being PATIENT (until it reaches optimum operating conditions by which time it's usually other peoples' bedtime).

Gimme a boomblaster

Tvad: I'm with you. Inversely, switches placed in the front can be left "on" 24/7 too. Cheers